Heat dissipation apparatus and fan frame thereof

ABSTRACT

A heat dissipation apparatus. A fan frame accommodates an impeller therein and includes an air inlet, an air outlet, and a passage for guiding airflow from the air inlet to the air outlet. An inner peripheral wall of the passage radially and outwardly extends a smooth curved expansion portion at the air outlet. The curved expansion portion includes a recess in which the airflow forms an airflow layer, stopping subsequent airflow from directly contacting the inner peripheral wall of the passage.

BACKGROUND

The invention relates to a heat dissipation apparatus and a fan frame thereof, and in particular to a fan and a fan frame providing reduced noise.

As performance of electronic devices is promoted, heat dissipation apparatuses or systems are indispensable and thus used in the electronic devices. If heat generated by an electronic device is not efficiently dissipated, performance of the electronic device may deteriorate or the electronic device may be damaged.

Fans serve widely as heat dissipation apparatuses. FIG. 1A is a schematic view of a conventional fan 1, and FIG. 1B is a schematic cross section taken along A-A′ of FIG. 1A. The conventional fan 1 is composed of a fan frame 11 and an impeller 12. When the fan 1 operates, the impeller 12 is activated by a motor 13, providing airflow to a heat source (such as a heat-generating electronic device, not shown) and thus dissipating heat therefrom. The fan frame 11 has a through hole forming an air inlet 112 and an air outlet 114 on two ends of the fan frame 11, respectively. The air inlet 112 is connected to the air outlet 114 by way of a central passage 116, such that the airflow provided by the impeller 12 can freely pass the air inlet 112 and air outlet 114. Additionally, four threaded holes 14 are formed on the corners of the fan frame 11, by means of which the fan 1 can be fixed to the shell of a system having electronic devices, such as a computer.

FIGS. 1C, 1E, and 1F are schematic cross sections of conventional fans and fan frames. A bevel angle C (as shown in FIG. 1C) or a tapered angle D (as shown in FIG. 1E) is formed near the air inlet 112 or air outlet 114 of the fan frame 11 in order to increase the area through which the airflow passes. As shown in FIG. 1D, although the bevel angle C increases the area of the air outlet 114, output airflow cannot be concentrated, thus reducing the airflow pressure provided by the fan frame 11. Alternatively, a recessed opening E (as shown in FIG. 1F) is formed near the air outlet 114 of the fan frame 11 by cutting parts of entirety of the fan frame, which is in order to increase the area through which the airflow passes. However, the airflow is easily dispersed from the recessed opening E.

Conventionally, when airflow passes through the air outlet 114, the airflow directly contacts the periphery of the inner wall of the central passage 116 (as shown in FIG. 1B), bevel angle C, tapered angle D, or wall of the recessed opening E. Accordingly, the airflow can not pass through the air outlet 114 smoothly and is slowed. Also, noise is generated by friction between airflow and the inner peripheral wall of the central passage 116. Specifically, the higher the rotational speed of the fan, the more the noise generated thereby.

SUMMARY

Hence, the invention provides a heat dissipation apparatus (a fan) and a frame thereof. The fan and fan frame has a smooth curved expansion portion capable of reducing noise generated by friction between airflow and the inner peripheral wall of the passage, stabilizing and concentrating the airflow, and enhancing performance of the fan. Moreover, the inner peripheral wall of the fan frame outwardly extends, increasing areas of air flow intake or discharge, concentrating the airflow, and enhancing performance of the fan. Further, the fan is easily applied to a heat dissipation system or any other electronic devices which generate heat by assembling without modifying arrangement of the system.

An embodiment of the invention provides a fan frame for a heat dissipation apparatus. The fan frame comprises a casing having a passage for guiding airflow from one opening to another opening. An inner peripheral wall of the passage radially and outwardly extends a smooth curved expansion portion at either one or both openings. The curved expansion portion further comprises a recess in which the airflow forms an airflow layer, stopping subsequent airflow from directly contacting the inner peripheral wall of the passage. The curved expansion portion is radially and outwardly extended out of the casing and is symmetrical with respect to an axis of the passage. Further, the curved expansion portion at either one or both openings has a tapered angle, a bevel angle, a tapered bevel angle, or a large R angle.

An inner peripheral wall of the passage radially and outwardly extends at the air inlet and is symmetrical with respect to the axis of the passage. Alternatively, an inner peripheral wall of the passage at the air inlet is radially and outwardly extended out of the casing and is symmetrical with respect to the axis of the passage. Alternatively, the inner peripheral wall of the passage at the air inlet radially and outwardly extends out of the casing in a circular or elliptical shape and is symmetrical with respect to the axis of the passage. The inner peripheral wall of the passage at the air inlet has a tapered angle, a bevel angle, a tapered bevel angle, or a large R angle with respect to the axis of the passage.

Another embodiment of the invention provides a heat dissipation apparatus comprising an impeller and a fan frame. The fan frame accommodates the impeller therein and comprises a passage for guiding airflow from one opening to another opening. An inner peripheral wall of the passage radially and outwardly extends a smooth curved expansion portion at either one or both openings. The curved expansion portion further comprises a recess in which the airflow forms an airflow layer so as to stop subsequent airflow from directly contacting the inner peripheral wall of the passage. The curved expansion portion is symmetrical with respect to the axis of the passage. Alternatively, the curved expansion portion is radially and outwardly extended out of the fan frame and is symmetrical with respect to the axis of the passage. The curved expansion portion at least one of the openings has a tapered angle, a bevel angle, a tapered bevel angle, or a large R angle.

The heat dissipation apparatus comprises an axial flow fan. The length of blades of the impeller is increased corresponding to the radially and outwardly extended curved expansion portion. The heat dissipation apparatus further comprises a motor base disposed in the fan frame. The impeller is disposed on the motor base. The motor base comprises a slope inclined radially, thereby increasing areas of air flow intake or discharge, and the slope is flat or curved. The fan frame is substantially rectangular, circular, elliptical, or rhomboid.

Still another embodiment of the invention provides a heat dissipation system comprising a system housing, at least one electronic device, and a heat dissipation apparatus. The electronic device is disposed in the system housing. The heat dissipation apparatus is applied to the system housing for dissipating heat generated by the electronic device during operation. The heat dissipation apparatus comprises an impeller and a fan frame accommodating the impeller. The fan frame comprises a passage for guiding airflow from one opening to another opening. An inner peripheral wall of the passage radially and outwardly extends a smooth curved expansion portion at either one or both openings.

DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1A is a schematic view of a conventional fan;

FIG. 1B is a schematic cross section taken along A-A′ of FIG. 1A;

FIGS. 1C, 1E, and 1F are schematic cross sections of conventional fan frames;

FIG. 1D is a schematic view showing the direction of air flow in the fan frame of FIG. 1C;

FIG. 2A is a schematic view of the fan of an embodiment of the invention;

FIG. 2B is a schematic cross section taken along B-B′ of FIG. 2A;

FIG. 3A is a schematic view showing the curved expansion portion F of FIG. 2B and the direction of air flow near the curved expansion portion F;

FIG. 3B is a schematic cross section of another fan frame of the invention;

FIG. 4 is a schematic view showing that the heat dissipation apparatus of the invention is applied to a system having electronic devices;

FIG. 5A and FIG. 5B are diagrams showing audio comparison of the conventional and present fans;

FIG. 6A and FIG. 6B are diagrams showing volume comparison of the conventional and present fans; and

FIG. 7 is a diagram showing characteristic comparison of the conventional and present fans.

DETAILED DESCRIPTION

Referring both to FIG. 2A and FIG. 2B, the heat dissipation apparatus 2 can be, for example, an axial flow fan and has a fan frame 21, an impeller 22, and a motor base 26. The fan frame 21 may be a substantially rectangular, circular, elliptical, or rhomboid casing. The fan frame 21 has a through hole so as to form a passage 216 therein, an air inlet 212, and an air outlet 214. The air inlet 212 is connected to the air outlet 214 by way of the passage 216. The passage 216 can guide airflow from one opening (air inlet 212) to the other opening (air outlet 214). Airflow generated by the impeller 22 can thus enter and leave the fan frame 21. Additionally, multiple threaded holes 24 are formed on corners of the fan frame 21 so that the fan 2 can be fixed to a housing of an electronic system, such as a computer.

The fan frame 21 accommodates the impeller 22 therein, and the motor base 26 is disposed in the fan frame 21. The impeller 22 is disposed on the motor base 26. When the fan 2 operates, a motor 23 disposed on the motor base 26 activates the impeller 22 so as to provide airflow to an electronic device (not shown) and dissipating the heat generated by the electronic device.

Referring to FIG. 2B and FIG. 3A, an inner peripheral wall of the passage 216 radially and outwardly extends a smooth curved expansion portion F at the air outlet 214. The curved expansion portion F includes a recess 218 in which the airflow forms an airflow layer so as to stop subsequent airflow from directly contacting the inner peripheral wall of the passage 216. Specifically, the airflow in the recess 218 provides an air cushion, thereby stopping subsequent airflow from directly contacting the frame wall of the fan frame 21. Accordingly, friction between air and solid is changed to friction between air to air, and noise is thus reduced. Moreover, the recess 218 of the curved expansion portion F provides sufficient space for airflow, whereby stabilizing the airflow. Additionally, when the airflow passes through the air outlet 214, the curved expansion portion F can sufficiently concentrate the airflow and enhance air pressure compared to the conventional fan frame 11 (FIG. 1D).

The curved expansion portion F is symmetrical with respect to the axis of the passage 216. Also, another curved expansion portion is radially and outwardly extended from the inner peripheral wall of the passage 216 at the air inlet 212. Moreover, the length of blades of the impeller 22 matches the fan frame 21 and is increased corresponding to the radially and outwardly extended curved expansion portion F so as to increase air volume. Preferably, the curved expansion portion F at the air outlet 214 may be formed with a tapered angle 219 a (FIG. 3A), a bevel angle, a tapered bevel angle, or a large R angle, so as to allow the airflow more smoothly passing through the fan frame 21.

Additionally, the inner peripheral wall of the fan frame 21 at the air inlet 212 may be formed with a bevel angle 219 b (FIG. 2B), a tapered angle, a tapered bevel angle, or a large R angle, increasing the area of the air inlet 212. Alternatively, the inner peripheral wall of the passage 216 at the air inlet 212 is radially and outwardly extended out of the fan frame 21 in a circular or elliptical shape and is symmetrical with respect to the axis of the passage 216.

Moreover, the curved expansion portion F may be radially and outwardly extended out of the fan frame 21 with respect to the axis of the passage 216 so as to increase the area through which the airflow passes.

FIG. 3B shows another fan frame of an embodiment of the invention. As the above mentioned, the present invention discloses the curved expansion portion F with a tapered angle at the air inlet 212 and/or air outlet 214, the motor base 26 may additionally include a slope 262 inclined radially to increase areas of air flow intake or discharge. The slope 262 is flat or curved.

In practical application, the heat dissipation apparatus 2 can be applied to a heat dissipation system 5 which includes a system housing 3 and multiple electronic devices, as shown in FIG. 4. Inside of the system housing 3, the electronic devices or heat sources are mostly on a circuit board 4, and the heat dissipation apparatus 2 is disposed within a suitable position of the system housing 3, such that cold airflow generated by the heat dissipation apparatus 2 is provided during operation to the electronic devices or heat sources. Accordingly, heat generated by the electronic devices is efficiently dissipated, and the electronic devices are thus prevented from damaging due to high temperature.

FIG. 5A is a diagram showing results of audio testing of a conventional fan. FIG. 5B is a diagram showing results of audio testing of the present fan. Both the conventional and present fans have a diameter of approximate 8 cm and were tested at speed of 5700 rpm. Comparing the results shown in FIG. 5A and FIG. 5B, the conventional fan incurs obvious noise at frequency of 665 Hz during operation while the present fan did not.

FIG. 6A is a diagram showing results of volume testing of a conventional fan. FIG. 6B is a diagram showing results of volume testing of the present fan. Both the conventional and present fans have a diameter of approximate 8 cm and were tested at speed of 5700 rpm. As shown in FIG. 6A, the noise value of the conventional fan at speed of 5700 rpm was 49.6 dB. As shown in FIG. 6B, the noise value of the present fan at the same speed was 46.7 dB. Accordingly, the present fan can effectively reduce noise compared to the conventional fan.

FIG. 7 is a diagram showing characteristic comparison of the conventional and present fans. Both the conventional and present fans have a diameter of approximate 8 cm and were tested at speed of 5700 rpm. As shown in FIG. 7, the present fan provides larger airflow pressure and volume compared to the conventional fan. Specifically, at an airflow volume of 40 CFM, the conventional fan provides an air pressure of 7.9 mmH₂O while the present fan provides an air pressure of 12.9 mmH₂O. As the results, the pressure provided by the present fan is increased by 63% compared to the conventional fan. Alternatively, at an air pressure of 10 mmH₂O, the conventional fan provides an airflow volume of 28.8 CFM while the present fan provides an airflow volume of 45 CFM. As the results, the airflow volume provided by the present fan is increased by 56% compared to the conventional fan. Accordingly, the present fan effectively enhances the air pressure and volume and thus rectifies the airflow.

In conclusion, the fans (heat dissipation apparatus) and fan frame of the present invention provide curved expansion portions capable of reducing noise from friction between airflow and the frame wall, thereby stabilizing the airflow, and thus enhancing performance of the fans. Moreover, without interfering with other heat dissipation devices originally disposed in the fans, the inner peripheral walls of the fan frames outwardly extend to increase the area through which the airflow passes, thereby enhancing heat dissipation of the fans. Further, the fan is easily applied to a heat dissipation system or any other electronic devices which generate heat by assembling without modifying arrangement of the system.

While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. 

1. A fan frame for a heat dissipation apparatus, comprising: a casing comprising a passage for guiding airflow from one opening to another opening, wherein the casing further comprises a smooth curved expansion portion being radially and outwardly extended from an inner peripheral wall of the passage at either one or both openings.
 2. The fan frame as claimed in claim 1, wherein the curved expansion portion further comprises a recess in which the airflow forms an airflow layer, stopping subsequent airflow from directly contacting the inner peripheral wall of the passage.
 3. The fan frame as claimed in claim 1, wherein the openings are an air inlet and an air outlet, and the smooth curved expansion portion is radially and outwardly extended from the inner peripheral wall of the passage at the air outlet.
 4. The fan frame as claimed in claim 3, wherein the curved expansion portion at the air outlet is radially and outwardly extended out of the casing and is symmetrical with respect to an axis of the passage.
 5. The fan frame as claimed in claim 3, wherein the curved expansion portion at the air outlet has a tapered angle, a bevel angle, a tapered bevel angle, or a large R angle.
 6. The fan frame as claimed in claim 3, wherein the casing further comprises another smooth curved expansion portion, being radially and outwardly extended from the inner peripheral wall of the passage at the air inlet, which is symmetrical with respect to an axis of the passage.
 7. The fan frame as claimed in claim 3, wherein the smooth curved expansion portion is radially and outwardly extended out of the casing from the inner peripheral wall of the passage at the air inlet and is symmetrical with respect to an axis of the passage.
 8. The fan frame as claimed in claim 3, wherein the smooth curved expansion portion is radially and outwardly extended from the inner peripheral wall of the passage at the air inlet in a circular or elliptical shape with respect to an axis of the passage.
 9. The fan frame as claimed in claim 3, wherein the inner peripheral wall of the passage at the air inlet has a tapered angle, a bevel angle, a tapered bevel angle, or a large R angle and is symmetrical with respect to an axis of the passage.
 10. A heat dissipation apparatus, comprising: an impeller; and a fan frame for accommodating the impeller therein and comprising a passage for guiding airflow from one opening to another opening, wherein the fan frame further comprises a smooth curved expansion portion being radially and outwardly extended from an inner peripheral wall of the passage at either one or both openings.
 11. The heat dissipation apparatus as claimed in claim 10, wherein the curved expansion portion further comprises a recess in which the airflow forms an airflow layer, stopping subsequent airflow from directly contacting the inner peripheral wall of the passage.
 12. The heat dissipation apparatus as claimed in claim 10, wherein the openings are an air inlet and an air outlet, and the smooth curved expansion portion is radially and outwardly extended from the inner peripheral wall of the passage at the air outlet.
 13. The heat dissipation apparatus as claimed in claim 10, wherein the length of blades of the impeller is increased corresponding to the radially and outwardly extended curved expansion portion.
 14. The heat dissipation apparatus as claimed in claim 10, wherein the heat dissipation apparatus is an axial flow fan.
 15. The heat dissipation apparatus as claimed in claim 10, further comprising a motor base disposed in the fan frame, wherein the impeller is disposed on the motor base, and the motor base comprises a slope inclined radially, thereby increasing areas of air flow intake or discharge.
 16. The heat dissipation apparatus as claimed in claim 15, wherein the slope is flat or curved.
 17. A heat dissipation system, comprising: a system housing; at least one electronic device, disposed in the system housing; and a heat dissipation apparatus applied to the system housing for dissipating heat generated by the electronic device, wherein the heat dissipation apparatus comprises an impeller and a fan frame for accommodating the impeller therein, the fan frame comprises a passage for guiding airflow from one opening to another opening, and the fan frame further comprises a smooth curved expansion portion being radially and outwardly extended from an inner peripheral wall of the passage at either one or both openings.
 18. The heat dissipation system as claimed in claim 17, wherein the curved expansion portion further comprises a recess in which the airflow forms an airflow layer, stopping subsequent airflow from directly contacting the inner peripheral wall of the passage.
 19. The heat dissipation system as claimed in claim 17, wherein the openings are an air inlet and an air outlet, and the casing further comprises a smooth curved expansion portion being radially and outwardly extended from the inner peripheral wall of the passage at the air outlet.
 20. The heat dissipation system as claimed in claim 19, wherein the curved expansion portion at the air outlet has a tapered angle, a bevel angle, a tapered bevel angle, or a large R angle. 